For safety purposes, make sure to remove all fuel lines, wires, and brake lines from underneath and around the floorpans you will be cutting. If you have a stock fuel system, the factory fuel line will be running along the passenger side framerail in the '71 Camaro. Again, we lucked out as all this was thrown in the garbage during the disassembly process.
We then cut out the pieces around the under-bracing to divide the floor into workable sections. Bob wielded the plasma cutter and made quick work of these sections. This is definitely a tool worth investing money in if you foresee cutting sheetmetal and performing fabrication such as this. The plasma cutter saves unbelievable amounts of time over a grinder or Sawzall.
After making our marks for the new floorpans, we ground down all the surface rust in the working area. This is essential, as we will be welding new sheetmetal on top of old and the last thing we want is rust to form between the two sheets. Once ground clean, it was all sprayed with weld-trough primer compliments of 3M.
We then did the same on the edges of our new floorpan and set it into place. Take your time lining this up because you don't want to have to cut out spot welds once tacked.
Once we were satisfied with placement, welding began. We jumped around in different spots of the floorpan to keep heat warpage to a minimum. We left 1/2- to 3/4-inch of overlap on the corners, as you can see. This will ensure that not only the welds, but the existing floor supports the new floorpan also.
We then flipped the body on the rotisserie and ground down all the welds. If you are doing this on the floor, make sure you have some jackstands and plenty of room to work.
Last but not least, we primed the entire floor pan and surrounding area with rust-proof primer. At this point, our passenger side floorpan was done and ready for some paint. Once both sides are complete, we will be going back and painting the underneath in gloss black and covering the cockpit with Dynamat sound deadening material.